Bookbinder

ABSTRACT

A binder for a stack of sheets including hinged covers with the binding portion of the first cover having posts which are bendable into vertical position to extend lockingly through aligned slits formed in the lateral edges of the sheets and with the binding portion of the opposite cover having loops in which the tips of posts are retainingly received. The binding portion of one of the covers has a flat backing sheet of metal secured to its outside surface with a terminal portion which flatly overlies the outside surface of the cover but which is bendable along a first scoreline to form a loop and bendable along a second scoreline to form a backing and with the terminal portion being subsequently looped and bent at 90* to form a finished edge which overlies the binding portion of the other cover. Means are provided for clamping the finished edge snugly in place.

Feb. 29,1972

United States Patent- Gustafson [54] BOOKBINDER Primary Examiner-Jerome Schnall [721 Invent w Nmndgh Attorney-Wolfe, Hubbard, Leydig, Voit & Osann, Ltd.

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binding portion of the first cover having posts which are 4 bendable into vertical position to extend lockingly through 2 1/ aligned slits formed in the lateral edges of the sheets and with the binding portion of the opposite cover having loops in [Sl] int. Cl. 13/08 [58] 7 Field of Search .................28l/25 R, 21 R, 29; 402/501, which the tips of posts are retainingly received. The binding portion of one of the covers has a flat backing sheet of metal secured to its outside surface with a terminal portion which Referen e Cited flatly overlies the outside surface of the cover but which is bendable along a first scoreline to form a loop and bendable UNITED STATES PATENTS along a second scoreline to form a backing and with the ter- 11/1920 Dawsonm""Wmmmmmm mmal portion being subsequently looped and bent at to tin/ 0 0 000 0/ 0 0 i 0 0 0 PATENTEDFEBZS I972 SHEET 1 [IF 2 Iowan-ran ARTHUR R. Gusmrsow %.'W\%,W%,M@QM

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SHEET 2 BF 2 Iuvcu FOR. ARTHUR R.Gus1-AF s0- 44 A'rrvs,

BOOKBINDER In my prior US. Pat. No. 2,743,467, which issued May 1, 1956, I disclosed a book binder and a machine for assembling it which constituted an improvement over binding systems available at that time. It is an object of the present invention to provide an improved binder for papers and records which is of inexpensive construction, which may be easily and quickly assembled by unskilled personnel and which has improved durability.

It is a more specific object to provide a binder which consists of a minimum number of components, mainly, a pair of covers having sheet retaining means and a backing member securely riveted in place plus a light clamping member. As-.

sembly is speeded and simplified, regardless of the thickness of the stack being bound, and the final result is of improved appearance as well as increased durability.

It is an important and related object to provide a binder for record sheets in which the narrow binding portions of the covers, which mount the sheet retaining means and which are relied upon to preserve the integrity of the volume, are inherently stronger than in my earlier construction, inasmuch as there is no necessity for cutting into the binding portion to form slits or notches which have an inevitable weakening effect. Moreover,'it is a characteristic of the new binder that the metal backing sheet which encloses the back of the volume, instead of being in the form of a separate, slipped-on piece, is permanently attached to the cover structure thus insuring that it will not be knocked off or torn loose as the volumes are subject to rough handling. Nonetheless, it is a feature of the present construction that the final clamping member may be intentionally released, enabling the backing element to be temporarily pushed out of the way for access to the cover and sheet-retaining means where it is necessary to add or remove pages.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which:

FIG. I shows a bound volume constructed and assembled in accordance with the present invention.

FIG. 2 is an exploded perspective showing the two cover assembliesand, an interposed sheet.

FIG. 3 is a fragmentary plan view of the inside surface of the lower cover member.

' FIG. 4 is a fragmentary plan view of the under surface of the lower cover member showing the profile of the integral backing sheet prior to bending.

FIG. 5 is a cross section taken along the line 5-5 in FIG. 3.

FIG. 6 is a comer detail of the lower cover assembly showing the manner in which the length of flat metal strip, secured to the inside surface, is bent to define a sheet returning strip or post.

FIG. 7 is a fragmentary view showing the inside surface of the upper cover member.

FIG. 8 is a fragmentary and enlarged end view of the upper cover as viewed along line 8-8 in FIG. 7.

FIGS. 9-15 inclusive are series of elevational views showing the assembling and binding procedure in which:

FIG. 9 shows the back cover assembly prior to assembly of sheets thereon.

FIG. 10 shows the sheets being assembled on the retaining strips or posts.

FIG. 10a is a fragmentary view showing use of a knife blade aligned with an upstanding post for automatic slitting of the sheets for post engagement.

FIG. 11 shows the bending over of the retaining strip and assembly of the upper cover thereon.

FIG. 12 illustrates the reverse bending of the backing sheet to form a first loop.

FIG. 13 shows the upward bending of the backing sheet.

FIG. 14 shows the terminal portion of the backing sheet bent to form a second loop.

FIG. 15 shows the loop being bent over the binding edge of the top cover to form a finished edge.

FIG. 16 is an enlarged fragment showing the profile of the finished edge with the clamping wire in place.

FIG. 17 is a fragmentary section taken along line 17l7 in FIG. 16 and showing the profile of the clamping wire.

While the invention has been described in connection with a preferred embodiment, it will be understood that I do not intend to be limited to the particular embodiment shown but intend, on the contrary, to cover the various alternative and equivalent constructions included within the spirit and scope of the appended claims.

Turning now to the drawings there is shown, in FIG. I, the appearance of a completed volume 20 having cover assemblies 21, 22 enclosing a stack of sheets 23 and protectively enclosed by an integral backing member 24. The covers are preferably formed of good quality, high-density-paper board or cardboard covered, either partially or wholly, by a glued-on layer of canvas or duck or other durable fabric. The backing member 24 is made of bendable metal also covered by a durable, preferably matching, fabric. The sheets comprising the stack 23 are neatly in register with one another and the final, bound product gives the appearance of an expensive professional binding job.

In the discussion which follows the cover assembly 21 will, for convenience, be referred to as the lower or bottom cover assembly, since it is this one which is first set in place in the assembling machine and upon which the sheets are assembled in registering relation. Similarly, the cover 22 will be referred to, for convenience, as the upper or top cover since it is the one which is last applied, although it will be understood that either of the covers may be the front" or the back cover of the volume, depending upon whether the sheets are assembled facedown or faceup.

Thus, referring to the lower cover assembly 21, it consists of a body portion 31, a narrow binding portion 32, which is preferably, although not necessarily, formed of the same material, and a hinge 33 interposed between them, the hinge being formed by the fabric covering 34 which bridges the gap between the members 31, 32.

Riveted longitudinally to the inner surface of the binding portion 32 of the cover is a length of fiat metal strip 40, the rivets being indicated at 41. The strip is reversely bent at a 45 angle as indicated at 42. In use the strip is again bent at a angle as indicated at 43 so that the ends of the strip, when in upstanding position, and lying in a common plane, form sheetretaining strips, or posts, 44 which are received in, and registered with, slits 45 formed in each sheet 46 parallel to the bound edge thereof 47.

For maximum compactness, the cover assemblies 21 are supplied with the sheet-retaining strips or posts 44 lying flat against the inner surface. Just prior to assembly of a volume the strips are bent from their flat position shown dot-dash in FIG. 6 to the upstanding position in which the strips are at right angles to the cover. The edge 48 of the fixed portion of the strip forms a convenient and well-defined bending guide which insures that the posts 44 will occupy a common plane when in their upstanding position.

Secured to the back side of the lower cover assembly 21 is a fiat backing sheet of metal which is covered with a layer of fabric facing the cover, and which is held securely and permanently by rivets to the backing portion 32, utilizing the same rivets 41 which are employed to hold the strip 40 discussed immediately above. The backing sheet 50, which is shown in profile in FIG. 4, has a first or bound edge 51 which is aligned with the edge of the member 32 to which it is secured, lateral edges 52, 53 which are aligned with the edges of the cover body, and a free or terminal portion 54 which defines a sufficient length, L, to permit the formation of a finished loop-type edge, suitable for clamping in place as a final step in the binding procedure. Moreover, the metal of which the backing sheet is made is preferably scored along line 55 which is parallel to the edge 51 and scored a second time along a parallel line 56, with the second scoring width, indicated at wt, being slightly greater than the first scoring width w for a purpose which will shortly appear. This scoring may be in the form of a groove in the metal, sufficiently deep so as to insure bending of the metal along a straight line yet sufficiently shallow so as not to appreciably interfere with the integrity of the metal.

The fabric layer on the metal backing, indicated at 57, covers at least the outwardly exposed surface, with the edges bent over and glued in place. However, because of the furnishing of the backing sheet facedown" on the cover to which it is permanently secured, the surface of the fabric which is exposed in use is kept in a clean, fresh and unfaded condition.

Turningattention next to the upper cover assembly 22 it is similar to the assembly 21, being made up of a body portion 61, a binding portion 62, and a hinge 63 which is formed by the fabric cover 64 the same as the hinge 33 in FIG. 5. Extending along the inner surface of the binding portion 62 is a length of flat metal strip 65, bent into loops 66, 67 at its ends and anchored in place by rivets 68. The size, particularly the length, of the loops is such as to snugly accommodate the tips of the sheet retaining posts 44 secured to the bottom cover.

The procedure for producing a completed binder using the cover assemblies at 21, 22 discussed above, while simple to describe, may be more readily understood by reference to the sequential views, FIGS. 9-15 inclusive.

Referring to FIG. 9, the bottom cover assembly 21 is placed in a suitable rack which serves to hold it stationary, permitting both hands of the operator to be used for assembling the sheets. The rack preferably forms part of an assembling machine with provision for feeding sheets downwardly in registered relation on the retaining posts 44. Reference is made to my prior patent for detailed disclosure of the machine. For present purposes, it will suffice to say that a slitting knife'is oriented in the plane of each of the posts with an effective cutting width which is just slightly greater thanthe width of the posts so that the sheets are automatically slit as they are pressed downwardly during the course of assembly.

Referring to FIG. a, a knife 70 is provided having an upwardly facing cutting edge 71 which is arranged at an angle and having a rear edge 72 which is closely spaced to, and in the plane of, the tip of the retaining strip. The knife blade 70 is supportingly sandwiched between a stationary support 73 and a clamping plate 74 held together by a screw 75. The blade supporting structure includes a side panel 76 which extends to within a short distance of the edge of the retaining strip 44. To feed a quantity of sheets 77 to the blade, a suitable hopper structure is provided including a ram head 79 which is notched to clear the blade and which serves to apply pressure evenly over the surface of the sheets. In placing the lower cover assembly 21 in the machine, the tips of the strips 44, after the strips are bent, are inserted into recesses just under, and in alignment with, the respective blades. Thus downward pressure applied to the sheets causes them to be slit along the lateral edges to a depth which is just slightly greater than the width of the retaining strips 44 and a continuation of the downward movement causes the sheets to be registered and retained in a neat, square stack. Reference is made to the above patent for further details. When all of the sheets have been thus assembled, the strips 44 are bent backwardly as shown in FIG. 11 and the upper cover assembly is slipped into place, with the then rearwardly extending strips being received in the loops 66, 67. With the top cover in place, as shown in FIG. 12, the strips 44 are bent downwardly along the back of the stack.

The flat backing sheet is bent about the first score line 55, reversely, to form a loop 81 having a smoothly finished appearance. The raw edge 51 is reentrant, or hidden.

Following this, as shown in FIG. 13, the backing sheet is bent upwardly along the second score line 56 forming a right angle bend 82 (FIG. 13) so that the backing sheet lies flatly against the back surface of the stack of sheets. The width w+ defined by the second score line is sufficiently greater than the width as to provide "radius stock for the two bends. The terminal portion, following the second bend, extends upwardly beyond the top cover assembly. Such upwardly projecting portion of the sheet is next bent reversely along a horizontal line to form a loop 83 which is located a distance w,or slightly more, above the top cover assembly. Where the thickness of the stack is indeterminate and where there can be no preestablished score line for the bend 83, the height of the line of reverse bending may be conveniently established by use of an anvil block 84 having a thickness w and which is positioned, as shown, on the top surface of the cover assembly 20 to provide a jig for bending the backing sheet through an angle of Following the bend through 90, the anvil 84 may be removed and the bend easily continued, by application of finger tip pressure to a full to form the loop.

As a final bending step, the upwardly extending portion of the backing sheet which is now of double thickness, is bent forwardly into a position overlying the binding portion of the top cover as shown in FIGS. 14, 15. The loop 83 produces a finished edge which is symmetrical with respect to the loop 81 and which has the same finished" appearance. The metal backing sheet is of such gauge and stiffness as to permit bending, even of the double thickness, with fingertip pressure although a gripping tool may be used if desired for the final bend. In a high-production setup the final bends are preferably done by the machine which is described in my prior patent.

For clamping the finishing loop 83 snugly in position, a length of wire 90 is preferably inserted into the loop 83 (FIGS. l6, 17) with tips 91, 92 which project sufficiently as to permit bending into C-shape about the ends of the binding portion 62. The bentover tips, 91, 92, are anchored against sliding movement by interference with the loops in the metal strip 65. The result is a bound volume which is easy to use, which is attractive in appearance, and capable of withstanding hard usage but which is, nevertheless, highly economical as regards both materials and assembly. Professional results may be secured following the simple assembly procedure outlined above, quickly and without necessity for using skilled personnel;

Since the two cover assemblies including the backing member are supplied completely flat, minimum storage space is required pending usage.

Since the backing sheet is integrally secured to one of the covers and securely clamped, by the wire, to the other, the bound volume is durable and permanent. However, it should be noted that when it is necessary to add or remove sheets the clamping wire may be unbent permitting the backing to be shoved backwardly and posts 44 straightened to permit removal of the top cover assembly for access to the sheets. It is not necessary to use the assembling machine described in my earlier patent for this and indeed, a volume may be assembled manually on a simple rack and in a little more time than it takes to use the assembling machine, particularly where the stack of sheets is preslit by cutting slit 45 to the appropriate depth at each end of the stack.

While the preferred form of the invention employs first and second score lines 55, 56, it will be understood that such score lines are not essential to the invention. Any suitable means may be employed for defining the location of the first bend 55. For example, a thin strip may be included under the heads of the rivets to provide a well defined bending edge, or the rivet heads themselves may be used to define the first bend. With regard to the second bend 56, a score line at this point is optional inasmuch as the edge of the binding portion to which the metal backing is attached may serve as an adequate benddefining medium. Thus, the term score line may be broadly interpreted as a line at which well-defined bending takes place even though such line is not defined by localized grooving or other deformation of the metal.

As used herein, the term fabric refers to any flexible, protective covering. The term stiff" or rigid as applied to the covers is a relative term and refers to any cover which is sufficiently rigid and self-supporting as to perform a protective function. The term hinge" is intended to cover not only use of fabric to define the region of bending but any construction where relative angular movement, whether or not sharply defined, may take place between the cover body and the narrow binding portion of the cover. While the term bendable metal" has been used in describing the backing of the binder, it will be understood that the term is used in a descriptive sense to apply to durable sheet materials capable of taking a permanent crease and that metal substitutes may be used which have characteristics similar to those of a metal such as soft steel. The term reversely bent" will be understood to apply to bending of the material back upon itself through 180".

While, in the embodiment shown, there is some projection of the outer covers beyond the stack of sheets, it will be apparent that this is a matter of the choice of the user. Indeed, it may be preferred to use sheets 46 which have a binding dimension greater than the sheets discussed above and which extend to the edges of the covers, making the volume flush along its lateral edges. In such event the slits 45 formed in the edges of the sheets are made relatively deeper, and the posts 44 which engage the slits would thus be embedded more deeply into the stack.

What I claim is:

1. A binder for binding a stack of uniformly sized sheets of paper into a book comprising, in combination, first and second stiff covers of matching configuration each having a body portion and a narrow binding portion with a hinge connection in between, the binding portion of the fu'st cover having a length of flat bendable metal strip secured longitudinally to its inside surface, the ends of the metal of strip being reversely bent at 45 so that the ends define sheet-anchoring posts which are bendable into a plane perpendicular to the binding portion for registering with aligned slits in the lateral edges of the stack of sheets, the binding portion of the second cover having a length of flat metal strip secured longitudinally to its inside surface, the ends of the metal strip being reversely bent to define loops for reception of the sheet-anchoring posts when the sheet-anchoring posts are retainingly bent over the top of the stack, the binding portion of one of the covers having a backing sheet of bendable metal secured to its outside surface, the sheet having substantially the same length as the cover and having a terminal portion which initially overlies the outside surface of the cover, said flat sheet of metal having a first score line to facilitate reverse bending into a loop and a second score line parallel thereto to facilitate bending at 90 to form a backing, the terminal portion of the metal sheet being sufficiently long as to permit reverse bending to form a loop and subsequent bending at 90 so that the loop overlies the binding portion of the other cover, and means for retaining the terminal portion of the backing sheet in snug engagement with the binding portion of the other cover.

2. The combination as claimed in claim 1 in which the covers and backing sheet have an adherent layer of fabric,

3. The combination as claimed in claim 1 in which the lengths of flat bendable metal strip and the metal backing sheet are secured to the binding portions of the respective covers by means of rivets.

4. The combination as claimed in claim 1 in which the means for retaining the looped and bent terminal portion of the backing sheet in snug engagement with the binding portion of the adjacent cover is in the form of a length of wire fed through the loop and inwardly bent at its ends to grip the binding portion.

5. A bound volume which comprises, in combination, a stack of uniformly sized sheets of paper having aligned slits along the lateral edges thereof adjacent the binding edge, first and second stiff covers of matching configuration each having a body portion and a narrow binding portion with a hinge in between, the binding portion of the first cover having a length of flat bendable metal strip secured longitudinally to its inside surface, the ends of the metal strip being reversely bent at 45 and bent at 90 so that the ends define sheet-anchoring posts extending perpendicularly to the plane of the first cover and registering with the aligned slits, the binding portion of the second cover having a length of flat metal strip secured longitudinally to its inside surface, the ends of the latter metal strip being reversely bent that the ends define loops in which the ends of the sheet-anchoring strips are retainingly received with the tips thereof being bent downwardly along the bound edge of the stack of sheets, and a C-shaped metal backing embracing the binding portions of the covers, said backing having means permanently attaching the same to the binding portion of one of the covers and having means for disengageable attachment to the binding portion of the other cover.

6. The combination as claimed in claim 5 in which the C- shaped backing has ends which are looped reentrantly to form a double thickness and in which one of the reentrant portions is permanently secured to the binding portion of the associated cover.

7. A binder for binding a stack of uniformly sized sheets of papers into a book, the sheets having aligned slits along their lateral edges near the bound edge thereof comprising, in combination, a bottom cover and a top cover, each cover having a body portion and a narrow binding portion with a hinge in between, the binding portion of the bottom cover having a length of flat metal strip riveted to its inside surface and with the ends of the metal strip being reversely bent at 45 so that the ends define sheet-anchoring strips which are bendable into a plane perpendicular to the binding portion and upon which the sheets'are registered with the strips engaging the aligned slits, the binding portion of the top cover having a length of flat metal strip riveted to its inside surface with the ends of the metal strip being reversely bent so that the ends define loops spaced of reception of the tips of the sheet-anchoring strips when the sheet-anchoring strips are retainingly bent over the top of the stack, the binding portion of the bottom cover having a flat backing sheet of metal riveted to its outside surface of substantially the same binding dimension as the cover and having a terminal portion which initially overlies the outside surface of the bottom cover, said backing sheet having means defining a line of bending adjacent the region of attachment for reverse bending of the sheet to form a loop and the metal being sufficiently thin as to permit bending upwardly by the figures of an operator to form a backing, the terminal portion of the sheet being sufficiently long as to permit reverse bending into a loop and subsequent bending of the loop at to form a finished edge which overlies the binding portion of the top cover, and means for retaining the finished edge in snug engagement with the binding portion of the top cover.

8. As an article of manufacture, a binder for binding a stack of uniformly sized sheets of paper into a book, the sheets having aligned slits formed in the lateral edges adjacent to the binding edge, comprising, in combination, first and second stiff covers of matching configuration each having a body portion and a narrow binding portion with a hinge in between, the binding portion of the first cover having sheet-anchoring strips flatly secured to its inside surface and bendable upwardly for registering with the aligned slits in the sheets, the binding portion of the second cover having means on its inside surface forming flat loops for receiving the tips of the anchoring strips, the tips at the region of passage through the loops being bendable retainingly about the bound edge of the stack, the binding portion of one of the covers having a flat backing sheet of metal secured to its outside surface and of substantially the same binding dimension as the covers and having a terminal portion which overlies the outside surface of the associated cover, said backing sheet having a first score line adjacent its region of attachment for reverse bending to form a loop and a second score line spaced to coincide with the edge of the associated binding portion for bending the backing sheet at 90 to form a backing, the tenninal portion of the metal sheet being sufficiently long as to permit reverse bending to form a second loop and subsequent bending of the looped edge at 90 to overlie the binding portion of the other cover, and, means for retaining the looped and bent terminal portion in snug engagement with the binding portion of said other cover.

9. As an article of manufacture, a binder for binding a stack of uniformly sized sheets of paper into a book, the sheets having aligned slits formed in the lateral edges adjacent to the binding edge, comprising, in combination, first and second stiff covers of matching configuration each having a body portion and'a narrow binding portion with a hinge in between, the binding portion of the first cover having sheet-anchoring metal strips secured to its inside surface and bendable upwardly into a common plane to form posts for registering with the aligned slits in the sheets, the binding portion of the second cover having strips of metal on its inside surface forming flat loops for receiving the tips of the anchoring strips, the tips at the region of passage through the loops being bendable retainingly about the bound edge of the stack, the binding portion of one of the covers having a flat backing sheet of metal secured to its outside surface and of substantially the same binding dimension as the covers and having a terminal portion which initially overlies the outside surface of the associated cover, said backing sheet having adjacent its region of attachment means permitting reverse bending to form a loop and a means for bending the backing sheet along a line which coincides with the edge of the associated binding portion to form a protective backing, the terminal portion of the metal sheet being sufficiently long as to permit reverse bending thereof to form a second loop and subsequent bending of the looped edge at to overlie the binding portion of the other cover, and means for retaining the looped and bent terminal portion in snug engagement with the binding portion of said other cover, the backing sheet having a covering of fabric on the surface which faces the cover to which it is secured for protection of the fabric against dirt or fading until the time of usage. 

1. A binder for binding a stack of uniformly sized sheets of paper into a book comprising, in combination, first and second stiff covers of matching configuration each having a body portion and a narrow binding portion with a hinge connection in between, the binding porTion of the first cover having a length of flat bendable metal strip secured longitudinally to its inside surface, the ends of the metal of strip being reversely bent at 45* so that the ends define sheet-anchoring posts which are bendable into a plane perpendicular to the binding portion for registering with aligned slits in the lateral edges of the stack of sheets, the binding portion of the second cover having a length of flat metal strip secured longitudinally to its inside surface, the ends of the metal strip being reversely bent to define loops for reception of the sheet-anchoring posts when the sheet-anchoring posts are retainingly bent over the top of the stack, the binding portion of one of the covers having a backing sheet of bendable metal secured to its outside surface, the sheet having substantially the same length as the cover and having a terminal portion which initially overlies the outside surface of the cover, said flat sheet of metal having a first score line to facilitate reverse bending into a loop and a second score line parallel thereto to facilitate bending at 90* to form a backing, the terminal portion of the metal sheet being sufficiently long as to permit reverse bending to form a loop and subsequent bending at 90* so that the loop overlies the binding portion of the other cover, and means for retaining the terminal portion of the backing sheet in snug engagement with the binding portion of the other cover.
 2. The combination as claimed in claim 1 in which the covers and backing sheet have an adherent layer of fabric.
 3. The combination as claimed in claim 1 in which the lengths of flat bendable metal strip and the metal backing sheet are secured to the binding portions of the respective covers by means of rivets.
 4. The combination as claimed in claim 1 in which the means for retaining the looped and bent terminal portion of the backing sheet in snug engagement with the binding portion of the adjacent cover is in the form of a length of wire fed through the loop and inwardly bent at its ends to grip the binding portion.
 5. A bound volume which comprises, in combination, a stack of uniformly sized sheets of paper having aligned slits along the lateral edges thereof adjacent the binding edge, first and second stiff covers of matching configuration each having a body portion and a narrow binding portion with a hinge in between, the binding portion of the first cover having a length of flat bendable metal strip secured longitudinally to its inside surface, the ends of the metal strip being reversely bent at 45* and bent at 90* so that the ends define sheet-anchoring posts extending perpendicularly to the plane of the first cover and registering with the aligned slits, the binding portion of the second cover having a length of flat metal strip secured longitudinally to its inside surface, the ends of the latter metal strip being reversely bent that the ends define loops in which the ends of the sheet-anchoring strips are retainingly received with the tips thereof being bent downwardly along the bound edge of the stack of sheets, and a C-shaped metal backing embracing the binding portions of the covers, said backing having means permanently attaching the same to the binding portion of one of the covers and having means for disengageable attachment to the binding portion of the other cover.
 6. The combination as claimed in claim 5 in which the C-shaped backing has ends which are looped reentrantly to form a double thickness and in which one of the reentrant portions is permanently secured to the binding portion of the associated cover.
 7. A binder for binding a stack of uniformly sized sheets of papers into a book, the sheets having aligned slits along their lateral edges near the bound edge thereof comprising, in combination, a bottom cover and a top cover, each cover having a body portion and a narrow binding portion with a hinge in between, the binding portion of the bottom cover having a length of flat metal strip riveted to its inside surface and with the ends of the metal strip being reversely bent at 45* so that the ends define sheet-anchoring strips which are bendable into a plane perpendicular to the binding portion and upon which the sheets are registered with the strips engaging the aligned slits, the binding portion of the top cover having a length of flat metal strip riveted to its inside surface with the ends of the metal strip being reversely bent so that the ends define loops spaced of reception of the tips of the sheet-anchoring strips when the sheet-anchoring strips are retainingly bent over the top of the stack, the binding portion of the bottom cover having a flat backing sheet of metal riveted to its outside surface of substantially the same binding dimension as the cover and having a terminal portion which initially overlies the outside surface of the bottom cover, said backing sheet having means defining a line of bending adjacent the region of attachment for reverse bending of the sheet to form a loop and the metal being sufficiently thin as to permit bending upwardly by the figures of an operator to form a backing, the terminal portion of the sheet being sufficiently long as to permit reverse bending into a loop and subsequent bending of the loop at 90* to form a finished edge which overlies the binding portion of the top cover, and means for retaining the finished edge in snug engagement with the binding portion of the top cover.
 8. As an article of manufacture, a binder for binding a stack of uniformly sized sheets of paper into a book, the sheets having aligned slits formed in the lateral edges adjacent to the binding edge, comprising, in combination, first and second stiff covers of matching configuration each having a body portion and a narrow binding portion with a hinge in between, the binding portion of the first cover having sheet-anchoring strips flatly secured to its inside surface and bendable upwardly for registering with the aligned slits in the sheets, the binding portion of the second cover having means on its inside surface forming flat loops for receiving the tips of the anchoring strips, the tips at the region of passage through the loops being bendable retainingly about the bound edge of the stack, the binding portion of one of the covers having a flat backing sheet of metal secured to its outside surface and of substantially the same binding dimension as the covers and having a terminal portion which overlies the outside surface of the associated cover, said backing sheet having a first score line adjacent its region of attachment for reverse bending to form a loop and a second score line spaced to coincide with the edge of the associated binding portion for bending the backing sheet at 90* to form a backing, the terminal portion of the metal sheet being sufficiently long as to permit reverse bending to form a second loop and subsequent bending of the looped edge at 90* to overlie the binding portion of the other cover, and, means for retaining the looped and bent terminal portion in snug engagement with the binding portion of said other cover.
 9. As an article of manufacture, a binder for binding a stack of uniformly sized sheets of paper into a book, the sheets having aligned slits formed in the lateral edges adjacent to the binding edge, comprising, in combination, first and second stiff covers of matching configuration each having a body portion and a narrow binding portion with a hinge in between, the binding portion of the first cover having sheet-anchoring metal strips secured to its inside surface and bendable upwardly into a common plane to form posts for registering with the aligned slits in the sheets, the binding portion of the second cover having strips of metal on its inside surface forming flat loops for receiving the tips of the anchoring strips, the tips at the region of passage through the loops being bendable retainingly about the bound eDge of the stack, the binding portion of one of the covers having a flat backing sheet of metal secured to its outside surface and of substantially the same binding dimension as the covers and having a terminal portion which initially overlies the outside surface of the associated cover, said backing sheet having adjacent its region of attachment means permitting reverse bending to form a loop and a means for bending the backing sheet along a line which coincides with the edge of the associated binding portion to form a protective backing, the terminal portion of the metal sheet being sufficiently long as to permit reverse bending thereof to form a second loop and subsequent bending of the looped edge at 90* to overlie the binding portion of the other cover, and means for retaining the looped and bent terminal portion in snug engagement with the binding portion of said other cover, the backing sheet having a covering of fabric on the surface which faces the cover to which it is secured for protection of the fabric against dirt or fading until the time of usage. 